ESPE Abstracts

Background: The common phenotype caused by NR5A1 mutations of 46,XY is gonadal dysgenesis without adrenal deficiency. Preserved fertility of the affected males was described in two patients with different mutations. No functional analysis of these two mutations has been done. Here we report brothers with isolated hypospadias who carries a novel heterozygous mutation of c.910G>A, E304K in NR5A1 gene. Their asymptomatic father carries the same nucleotide change in heterozygous state, indicating fertility.

Objective: To clarify the molecular mechanism of preserved fertility in the family.

Case: A 3-month-old boy presented penoscrotal hypospadias at birth. He had no other manifestations including adrenal deficiency. His karyotype was 46,XY. His elder brother also presented hypospadias at birth with no other manifestations. At present, younger and elder brothers are 13 and 16 years old, respectively. Spontaneous puberty developed in both brothers. Because both brothers were affected, we analyzed candidate genes for hypospadias and identified the novel mutation described above.

Methods: We generated NR5A1 expression vector containing WT and E304K, which were transiently transfected in COS-1 cells. Using the constructs, western blot analysis, immunofluorescence assay, electrophoretic mobility shift assay and Luciferase assay were performed.

Results: WT and E304K proteins were expressed in comparable amounts and localized exclusively to the nucleus. DNA binding affinity of E304K was decreased. Transcriptional activity of E304K was diminished down to 40% compared to WT in Luciferase assay. No dominant negative effect was observed.

Conclusion: E304K showed residual DNA binding affinity and transcriptional activity. We assume that those residual functions led to preserve fertility.